The American pica of 0.16604 inches (4.217 mm). It was established by the United States Type Founders' Association in 1886.[1][2] In TeX one pica is ​12⁄72.27 of an inch.

The contemporary computer PostScript pica is exactly ​1⁄6 of an inch or ​1⁄72 of a foot, i.e. 4.233 mm or 0.166 inches.

Publishing applications such as Adobe InDesign and QuarkXPress represent pica measurements with whole-number picas left of a lower-case p, followed by the points number, for example: 5p6 represents 5 picas and 6 points, or 5​1⁄2 picas.

The pica is also used in measuring the font capacity and is applied in the process of copyfitting.[4] The font length is measured there by the number of characters per pica (cpp). As books are most often printed with proportional fonts, cpp of a given font is usually a fractional number. For example, an 11-point font (like Helvetica) may have 2.4 cpp,[5][6] thus a 5-inch (30-pica) line of a usual octavo-sized (6×8 in) book page would contain around 72 characters (including spaces).[7][8]

There have existed copyfitting tables for a number of typefaces, and typefoundries often provided the number of characters per pica for each type in their specimen catalogs. Similar tables exist as well with which one can estimate the number of characters per pica knowing the lower-case alphabet length.[9]

The typographic pica must not be confused with the Pica font of the typewriters, which means a font where 10 typed characters make up a line one inch long.